"use strict";

var s = new Set();
[2, 3, 5, 4, 5, 2, 2].forEach(function (x) {
  return s.add(x);
});
var numbers = [5, 6, 13, 0, 1, 2]; //1个参数时可带括号或者不带括号

var _double = numbers.map(function (number) {
  return 20 * number;
});
